Focus On... Rabies: Vaccinating Dogs, Saving Human Lives

After a major outbreak of rabies in the Bukowina in 1891, the Supreme Sanitary Board of Austria formed an Epidemiologic Committee, which finally recommended the establishment of a vaccination unit in a hospital.  In July 1894 the Vaccination Unit was opened in the Viennese hospital Rudolfstiftung, and Emerich Ullmann, a previous assistant to Louis Pasteur, carried out the rabies vaccinations1.  That was over 120 years ago, and yet rabies is still one of the greatest infectious threats to kill humans globally.

Rabies is estimated to be responsible for between 55,000 and 70,000 human deaths a year.  A large proportion of those affected are children.  It is estimated to cost $8.6 billion a year globally.  And yet, despite this, it is a neglected disease.  While rabies prevention and control provide probably the best example of “One Health”, intersectoral challenges are also its downfall. Human and veterinary health authorities often are unable to agree on which should fund the most effective intervention in terms of disease control, namely; dog vaccination.

dogs

Rabies Control

It is clear that culling does not work2.  Not ignoring the fact that the methods of culling are almost always inhumane ways leading to suffering, rabies deaths in humans don’t go down where dog culling has been carried out. In fact, the situation can get worse.  There are probably a few reasons for this.  Firstly villagers become scared of authorities and hide dogs.  Instead of developing a trusting relationship with education as a cornerstone, culling drives the wrong behaviours in people, including moving dogs to other areas and thus spreading the disease further.  Secondly, culling changes the dog population dynamics, leaving territorial gaps for new ownerless animals to move into and increasing the acquisition rate of owned dogs to replace those that have been killed – all of which may also drive the spread of rabies.  Recent studies have demonstrated that low-density dog populations and high-density dog populations have a similar rate of spread of disease. Therefore, reducing dog population density is unlikely to be an effective strategy3.

Education

Humans and dogs have an intricate relationship going back at least 100,000 years; there is an element of interdependency that goes beyond the working one.  There are social aspects that are just as important.  These have to be considered in any attempt to control disease.  While these can be barriers when handled incorrectly, they can also simplify the process, as understanding leads to a desire to control the disease.

15 years ago vaccinating dog populations seemed an almost impossible task as the number of stray dogs seemed insurmountable.  However, in the last decade we have developed a better understanding of the role of dogs in society.  The term “stray” has been replaced by the more accurate one of “free roaming”.  A lot of these dogs do have owners and homes, and can be reached through proper targeted strategies4.  Effective engagement of local communities can result in vaccination campaigns that reach 90% or more of the dog population.

Success of Vaccination

Implementing vaccination campaigns aimed at the domestic dog population is key to the successful control of canine rabies, and a strong body of evidence indicates that vaccinating 70% of the dog population should be sufficient to control the disease4.  Numerous campaigns have demonstrated that vaccinating dogs will reduce rabies exposures and prevent rabies cases in humans.  For instance, increasing dog vaccination in Sri Lanka has brought the incidence in humans down from 2 cases in every 100,000 people to around 0.25 in 20055.  Dog-mediated human rabies is on the brink of elimination in Latin America as a result of mass dog vaccination campaigns.  

Dog

Summary

Despite this, it is very easy to become overly focused on potential hurdles.  Yes, for global eradication we cannot ignore wildlife - bats are causing an increasing number of human rabies deaths in South America, and there are wildlife cycles of rabies sustained by raccoons, skunks and foxes in North America.  But the majority of human cases of rabies result from dog bites, not from wildlife.  On the whole, elimination of human deaths and elimination of canine rabies can be achieved without focusing on wildlife.  In fact, in most parts of Africa and Asia, vaccinating dogs is also likely to lead to the disappearance of rabies in wildlife.   In the Serengeti, the wild dog population has recovered in response to the vaccination campaigns in domestic dogs6.

It’s easy to get drawn into focusing on the complex issues of rabies, and then the goal of eradicating rabies becomes overwhelming.  However, we can already achieve at least 90% of the goal of human rabies prevention by the simple act of vaccinating dogs.  Initiating vaccination programmes for dogs can quickly have a massive positive impact on human health, and lead to long term financial improvement within the country, as fewer doses of the costly post-bite preventative treatment is required for people exposed to rabies.

1 Flamm H. Pasteur’s rabies vaccination: 130 years ago successfully started in Vienna, however officially rejected. Wiener Medizinische Wochenschrift. 2015;165(15-16):322-339.
2 Rabies: Scientific Basis of the Disease and Its Management. Jackson, A.C., Third Edition 2013.
3 Morters MK, Restif O, Hampson K, Cleaveland S, Wood JL, Conlan AJ, Boots M. Evidence based control of canine rabies: a critical review of population density reduction. J Anim Ecol. 2013;82(1):6-14.
4 Morters MK, McNabb S, Horton DL, Fooks AR, Schoeman JP, Whay HR, et al. Effective vaccination against rabies in puppies in rabies endemic regions. Vet Rec. 2015;177(6):150.
5 Rabies in the South East Asia Region, WHO publication website. Accessed September 11, 2015.
6 Cleaveland S, Eblate E. Recovery of endangered dogs. Veterinary Times. 45(33):2015.

 

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